Databases
What is database...
What is, an organized collection of structured information, or data.
What is the first rule of normalization...
What is, A table shall contain no repeating groups.
How do you resolve a many-to-many relationship using an intersection entity?
What is, the intersection entity contains an attribute connecting both entities after turning them into one-to-many relationships.
What are common data types used in relational databases? (get 2)
What is, Common data types in relational databases include INT for integers, VARCHAR for variable-length strings, DATE for date values, DECIMAL for fixed-point numbers, and BOOLEAN for binary values (true/false).
What is data abstraction?
What is, Data abstraction is a programming and design tool that displays basic information about a device while hiding its internal functions.
Name three types of database models...
What is, Hierarchical databases. Network databases. Relational database
What is the second rule of normalization...
What is, If fields in a table depend on only part of a compound primary key, move them to a separate table.
Define a barred relationship.
What is, the relationships from the originating entities to the intersection entity.
How do you identify foreign keys from an ERD?
What is, often marked with "FK" or a similar notation to indicate the foreign key.
What is the difference between logical and physical data model?
What is, Logical considers specific database implementation details, while physical databases considers every detail to make into a database.
What is a flat-file database, and how does it differ from a relational database?
What is, A flat file is usually a table with rows of information, whereas a relational database contains many tables with rows and columns that recognize relationships between different pieces of information.
What is the third rule of normalization...
What is, If any fields in a table don't depend on the primary key, move them and the fields they depend on to a separate table.
What is a composite unique identifier?
What is, A UID with a combination with attributes.
What is the purpose of a foreign key in a relational database?
What is, A foreign key is used to establish and enforce a link between the columns in two tables, representing a relationship. It ensures referential integrity.
What is WHERE...
What is, WHERE is an SQL Statement that is used to specify what data is being specified.
List and describe the components of a database system. (get 3).
What is, hardware, software (Database Management System - DBMS), data, procedures, and database access language.
What is fully functional dependency...
What is, The entity has a fully functional if both A & B are required to know the C & D values.
Why is it necessary to track data changes over time in a database?
What is, Allows for the creation of reports that provide valuable information to the organization's leadership.
Describe the relationship between primary keys, composite primary keys, and foreign keys.
What is, A primary key uniquely identifies records in a table, while a composite primary key consists of two or more columns to form a unique key. Foreign keys link a table to another by referencing the primary key of the related table, enforcing referential integrity.
What will the statement “SELECT * FROM WHERE” output?
What is, This statement will select everything and then pick out specified information.
Describe the three levels of data abstraction in relational databases...
What is, Physical level (lowest), Conceptual level (middle), and External level (highest).
What is database normalization?
What is, involves organizing database tables to reduce data redundancy and improve data integrity.
What are the similarities and differences between an arc relationship and a supertype/subtype entity?
What is, (Hierarchical structure, common attributes, exclusivity, and specific usage.
What are candidate keys, and how do they differ from primary keys?
What is, Candidate keys are attributes or combinations of attributes that could potentially be used as a primary key, while the primary key is the chosen candidate key that uniquely identifies records.
DAILY DOUBLE!!!
What will this statement output:
SELECT Orders.OrderID, Customers.CustomerName, Orders.OrderDate
FROM Orders
INNER JOIN Customers
ON Orders.CustomerID=Customers.CustomerID;
What is, This statement will output all information from OrderID, CustomerName, OrderDate.